I just saw an ad for frozen avocado.

This is a new one to me. How do they hold up to freezing and what can or can't they be used for? I don't plan on buying a commercial version but as someone who is somewhat challenged in the area of predicting if a given avocado will be edible on a given day the concept of them waiting in the freezer for me completely ripe is appealing.

Lemon juice wouldn't have affected the browning at all. An avocado browning, like an apple, comes from oxidisation, and the only way to prevent that is to not expose the cut fruit to air for any length of time.